Even if every fan who ever watched a hockey game stopped attending NFL football games, they would still make money. The NFL doesn't even need attendence (regular seats) to break even. If no one showed up for an NFL game (assuming the luxury boxes were paid for), the NFL would still make money. We couldn't hit their wallets hard enough to make them do anything.

And I doubt, even if we did make an impact, that the other leagues would actually correlate the two.